Device for extinguishing film fire



June 8, 1954 I R. ASHLEY ETAL DEVICE FOR EXTINGUISHING FILM FIRE} Filed Dec. 10, 1951 ,fayma/m Ash/ey Tom 4/. Fa 5 b INV TOR.

BY H 20 Patented June 8, 1954 UNITED STATEfi PATENT OFFICE 2,680,489 DEVICE FOR EXTINGUISHING FILM FIRE Raymond Ashley and Tom J. Fatjo, Richmond, Tex.

Application December 10, 1951,

4 Claims.

This invention relates to a device for extinguishing the fire of a burning film in the magazine of a motion picture projection machine.

The type of films used in the motion picture industry today may be divided into two general classes, viz.: the type commonly referred to in the trade as nitrate film, such as cellulose nitrate or the like, and the type commonly referred to in the trade as safety film, such as cellulose acetate or the like. While safety film is far less a. fire hazard than nitrate film, the latter is still being Widely used because of its superiority in certain other respects. One such disadvantage is that safety film is much thicker than nitrate film and far more difficult to splice.

The chief and practically the only disadvantage of nitrate film is the very serious fire hazard created by its use. It is highly inflammable, ignites with extreme ease, and burns with almost explosive Violence. Its fast rate of burning is quite like that of a deflagrating explosive. Not infrequent ignition of the film is that caused by the intensified projection machine are light used to project the picture on the screen.

A major difficulty involved in extinguishing nitrate film fires arises from the fact that several hundred feet of the film is wound upon itself on a reel enclosed in clearances between the film Therefore, the film is practically inaccessible for the purpose of extinguishing a film fire.

A number of devices have been proposed for extinguishing nitrate film fires, but, insofar as we are aware, none of them have solved the problem to such extent as to enjoy general acceptance and use by the industry. It almost goes without saying, that conventional containers in which the usual fire extinguishing agents are supplied for use, are highly inadequate for extinguishing nitrate film fires.

An object of he present invention is to provide a device for extinguishing nitrate film fires. A further object is to provide such a device which is efiicient, reliable, and economical and which completely extinguishes the fire in a Very short sonnel or equipment and before it has damaged any substantial portion of the film. The above and other objects will be apparent from the description of this invention given hereinafter.

This invention will be more readily understood by describing a preferred embodiment thereof with reference to the accompanying drawings.

Referring to the drawings generally:

Figure l is a plan View showing the device of has damaged per- Serial No. 260,872

this invention installed in a motion picture projection room.

Figure 2 is an isometric view showing certain details of this invention from which the film reel has been removed.

Figure 3 is a side elevation showing the device of this invention as viewed from the door side of the motion picture magazine with the door thereof closed.

Figure 4 is a cross section view i 5 of Figure 2, showing details spray heads of this invention.

Referring to the drawings in greater detail:

Numeral l designates a magazine of the motion picture projector divided essentially into a door 2 hinged 3 to the primary housing portion 4. reel (not shown) upon which a film 5 is wound fits over and rotates about the housing concentric therewith. The length along the line of one of the of the picture, the average length film being several hundred feet (e. g. 10OG-2090 feet). The film width is standard. In any event there is only a small fraction of an inch clearance between the film reel and the magazine. This makes it extremely difficult to reachthe film with fire extinguishing material without opening the magazine door 2. opening the door 2 is entirely unsatisfactory because the side of the film opposite the door is still inaccessible, and because opening the door greatly promotes burning of the film by creating a draft and increasing the quantity of oxygen.

We have found that in order to effectively and properly extinguish such a film fire it is necessary to provide a means of rapidly contacting substantially the entire area of all exposed surfaces of the film at practically the same time with fire extinguishing material under ressure without opening the door of the magazine. One practical and effective way we have developed which accomplishes this result includes the following preferred embodiment of the present invention.

A number of spray heads '5 and la, more fully described hereinafter, are removably secured in the door 2 of the magazine l. A number of similar spray heads 8 and 8a are duit 9 extends from the hose as of a conventional fire extinguisher l i, which may be conveniently located on a support 52 on the outside of a projection room l3 near the door M thereof, then extends up to and along the ceiling of the projection room to a point thereon above the magazine Then the conduit 9 extends downwardly and branches int-o conduits i6 and l! which extend to the magazine door 2 and the magazine housing respectively. Conduit l5 branches into the form of an H over the magazine door, with branch conduits a and i6?) communicating with the spray heads 1 and 1a, respectively. Conduit ii likewise branches into the form of an H over the housing d, with branch conduits Ho: and ill) communicating with the spray heads 8 and 3-1. respectively. In order to avoid the magazine i being rigidly fixed by the conduit s, preferably conduit 53 will communicate with branch conduits it and ii through flexible couplings 18, such as e, g. a hose or a flexible metal tubing.

For the sake of convenience and econom perierably the conduits will be standard pipe or tubing. In this event, as will be apparent from the detail description of a preferred type or spray head given below, the branch conduits may communicate with the spray heads through standard fittings (such as Ts, Ls, etc).

We have obtained excellent results by making the spray heads from a stock blank fitting 15 (Figure a) in the general shape of an hexagonal rod. The rod is machined in such manner as to produce the head 28), shoulders 2!, and body .22 having standard threads 23. Generally a plurality of side jets 2d and a center jet 2% are drilled in the head We have obtained good results with six equally spaced side jets and one center jet, but the number of jets and spacing thereof are not critical so long as the other conditions described herein are substantially met. Then the spray head is placed in an opening 25 made therefor in the wall of the magazine I such that the head is directed toward the inside of the magazine. The spray head then is secured to the magazine and connected to one of the branch supply conduits (described above) by means of a standard L 21.

Our experiments have shown that in order to extinguish a nitrate film fire, a means must be provided for rapidly contacting substantially the entire exposed surfaces of the film at practically the same time, and that this must be accomplished without opening the door of the magazine. In order to accomplish this result, the spray heads must be substantially geometrically located in a general symmetrical. pattern with respect to the magazine and the angle of the side jets must be within certain limits. Because of the location of the window 28 in the door 2 in the magazine 1, it is impractical to geometrically locate the spray heads in the door; however, they can be made to approach such location near enough to be adequate for the purpose described. Further, in order to accomplish this result, the angle which the side jets form with the side walls of the magazine (i. e. angle A shown in Figure 4) must fall within certain fairly well defined limits. While satisfactory results are obtained when the magnitude of this angle is 15 to 45, it must not go outside these limits to any appreciable extent; and we obtain better results if the magnitude of this angle is about 18-2 l. While the angle which the center jet forms with the side walls of the magazine is not critical, we have obtained excellent results when this angle was 90 and we prefer to use an angle of this magnitude.

W e have performed a series of tests in which nitrate film fires were extinguished with the above described device with all significant conditions substantially as they would occur by accidental ignition of a nitrate film while showing a picture. In these tests a nitrate film was placed in a magazine of a motion picture projector. The film was purposely ignited and allowed to burn, with the magazine door closed, until the fire had approached its peak but not long enough to blow open the door or rupture the magazine by developed pressure. At this point the fire extinguisher H (containing alkali metal salts in solution as the fire extinguishing fiuid) was inverted. In all tests this completely extinguished the film fire within a very few seconds after inverting the fire extinguisher. The film did not re-ignite upon standing 30 minutes. In a second series of tests the conditions were further accelerated over those encountered in actual use. In these tests the film was ignited by sprinkling lighter fluid on the film before ignition. The film then was ignited and allowed to burn as in the first series of tests before inverting the fire extinguisher. In all tests this completely extinguished the film fire within a very few seconds after inverting the fire extinguisher. The film did not re-ignite upon standing 30 minutes.

In motion picture projection machines, there are two magazines which are arranged in substantially identical pairs one above the other. In projecting a picture onto the screen, the film is unwinding from the reel in the top magazine and onto the reel in the bottom magazine. Only the top magazine is shown in the drawings or" this invention. Obviously, we may provide a means according to our invention for extinguishing any fire which might occur in the bottom magazine; however, practically all film fires occur in the top magazine.

Although not per se a part of our invention, we may use any conventional type fire extinguishing material suitable for extinguishing nitrate film fires. We have obtained best results by employing the fire extinguishing material comprising in solution alkali metal salts, which material is sold under the trade name of Karbaloy. While we can use other conventional fire extinguishing materials (such as e. g. soda-acid mixture, or a mixture comprising water and one or more wetting agents, the latter mixture being known in the trade as wet water), they are less desirable.

The fire extinguisher container may be inverted by hand or by various well-known automatic means.

As many apparently widely dificrent embodi ments of this invention may be made without dcparting from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.

What is claimed is:

1. In a device for extinguishing film fires adapted to be connected to a container of fire extinguishing material, a cylindrical film reel receiving magazine having substantially parallel side walls, a plurality of spray heads substantially symmetrically arranged respectively in each of the side walls of the magazine, at least one jet in each of said spray heads, said jet forming with the side walls an angle of 15-45, and conduits for transmitting fire extinguishing material from said container to said spray heads, whereby substantially the entire area of all exposed surfaces of the film will practically simultaneously be covered with the fire extinguishing material.

a device for extinguishing film fires ed to a container of fire the film will practically simultaneously be cova cylindrical film reel ered with the fire extinguishing material upon 'ng substantially parallel discharge of the contents of said container.

of spray heads substan- 4. In a device for extinguishing film fires forming with in one side wall being staggered with respect ously be side walls a substantially right angle, and cong magazine, a plurality of taneously be covered with the fire extinguishing gered with respectto References Cited in the file of this patent UNITED STATES PATENTS an angle of eighteen to Number me Date and means to connect said 1,7 6 Wright Jan. 27, 1931 container whereby substan- 1,303,859 a G e o M y 5, 931

a of all exposed surfaces of 9 3 Lincoln ay 1934 

